A conventional semiconductor laser diode is small in optical power at a constant operating current and limited in ridge width when integrated with an optical device, which forces the integration to be performed by lowering the original characteristic and makes it difficult to reduce cost and power consumption. In a semiconductor laser diode, widening of the ridge width is made possible by lowering the difference in refractive indexes between the ridge and other components, diffusion current and increase in the difference of refractive indexes are prevented by forming approximately vertical grooves along both sides of the ridge, and deterioration in characteristics due to regrowth is prevented by forming a diffraction grating on the ridge. The semiconductor laser diode is integrated with an optical device such as electroabsorption type optical modulator without increase of growth cycles and without restriction of the ridge width by using a tapered waveguide.